Java中怎么实现一个计算器小程序,很多新手对此不是很清楚,为了帮助大家解决这个难题,下面小编将为大家详细讲解,有这方面需求的人可以来学习下,希望你能有所收获。代码如下:package tst.jframe; impor
Java中怎么实现一个计算器小程序,很多新手对此不是很清楚,为了帮助大家解决这个难题,下面小编将为大家详细讲解,有这方面需求的人可以来学习下,希望你能有所收获。
代码如下:
package tst.jframe; import java.awt.EventQueue;import java.awt.event.ActionEvent;import java.awt.event.ActionListener;import javax.swing.JButton;import javax.swing.JFrame;import javax.swing.JTextField;import java.awt.Font;import javax.swing.SwinGConstants; public class javaAP { private JFrame frame; private JTextField result; private JButton button_1; private JButton button_2; private JButton button_3; private JButton button_4; private JButton button_5; private JButton button_6; private JButton button_7; private JButton button_8; private JButton button_9; private JButton button_0; private JButton Button_equal; private JButton button_dot; private JButton button_d0; private JButton button_plus; private JButton button_sub; private JButton button_clr; private JButton button_dlt; private JButton button_mul; private JButton button_div; private boolean numflag = false; //用于标识是否输入数字 private boolean opflag = false; //用于标识是否输入运算操作符 private String txt = null; //显示结果的文本框的文本内容,用于存放计算结果的字符串形式 private String num_txt = ""; //每次输入一个数,以字符的形式加到该字符创变量,后面运算直接将该字符创转成double类型进行运算 private String op = " "; //存放输入的运算操作符 private double num1 = 0; //num1和num2用作运算 private double num2 = 0; public static void main(String[] args) { EventQueue.invokeLater(new Runnable() { public void run() { try { javaAP window = new javaAP(); window.frame.setVisible(true); } catch (Exception e) { e.printStackTrace(); } } }); } public javaAP() { initialize(); } private void initialize() { frame = new JFrame(); //----------------------------------------------- frame.setResizable(false); // frame.setBounds(100, 100, 371, 371); // 窗口各个属性的初始化 frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); // frame.getContentPane().setLayout(null); //----------------------------------------------- result = new JTextField(); //----------------------------------------------- result.setFont(new Font("Lao UI", Font.BOLD, 15)); // result.setHorizontalAlignment(SwingConstants.RIGHT); // result.setBounds(29, 28, 308, 50); // 显示结果的文本框的各个属性的初始化 frame.getContentPane().add(result); // result.setColumns(10); // result.setText(txt); //----------------------------------------------- button_0 = new JButton("0"); button_0.addActionListener(new ActionListener() { public void actionPerfORMed(ActionEvent e) { numBtnAction("0"); } }); button_0.setBounds(99, 273, 50, 50); frame.getContentPane().add(button_0); button_1 = new JButton("1"); button_1.addActionListener(new ActionListener() { public void actionPerformed(ActionEvent e) { numBtnAction("1"); } }); button_1.setBounds(99, 213, 50, 50); frame.getContentPane().add(button_1); button_2 = new JButton("2"); button_2.addActionListener(new ActionListener() { public void actionPerformed(ActionEvent e) { numBtnAction("2"); } }); button_2.setBounds(159, 213, 50, 50); frame.getContentPane().add(button_2); button_3 = new JButton("3"); button_3.addActionListener(new ActionListener() { public void actionPerformed(ActionEvent e) { numBtnAction("3"); } }); button_3.setBounds(219, 213, 50, 50); frame.getContentPane().add(button_3); button_4 = new JButton("4"); button_4.addActionListener(new ActionListener() { public void actionPerformed(ActionEvent e) { numBtnAction("4"); } }); button_4.setBounds(99, 157, 50, 50); frame.getContentPane().add(button_4); button_5 = new JButton("5"); button_5.addActionListener(new ActionListener() { public void actionPerformed(ActionEvent e) { numBtnAction("5"); } }); button_5.setBounds(159, 157, 50, 50); frame.getContentPane().add(button_5); button_6 = new JButton("6"); button_6.addActionListener(new ActionListener() { public void actionPerformed(ActionEvent e) { numBtnAction("6"); } }); button_6.setBounds(219, 157, 50, 50); frame.getContentPane().add(button_6); button_7 = new JButton("7"); button_7.addActionListener(new ActionListener() { public void actionPerformed(ActionEvent e) { numBtnAction("7"); } }); button_7.setBounds(99, 97, 50, 50); frame.getContentPane().add(button_7); button_8 = new JButton("8"); button_8.addActionListener(new ActionListener() { public void actionPerformed(ActionEvent e) { numBtnAction("8"); } }); button_8.setBounds(159, 97, 50, 50); frame.getContentPane().add(button_8); button_9 = new JButton("9"); button_9.addActionListener(new ActionListener() { public void actionPerformed(ActionEvent e) { numBtnAction("9"); } }); button_9.setBounds(219, 97, 50, 50); frame.getContentPane().add(button_9); button_dot = new JButton("."); button_dot.addActionListener(new ActionListener() { public void actionPerformed(ActionEvent e) { numBtnAction("."); } }); button_dot.setFont(new Font("宋体", Font.BOLD, 15)); button_dot.setBounds(159, 273, 50, 50); frame.getContentPane().add(button_dot); button_d0 = new JButton("00"); button_d0.addActionListener(new ActionListener() { public void actionPerformed(ActionEvent e) { numBtnAction("00"); } }); button_d0.setBounds(219, 273, 50, 50); frame.getContentPane().add(button_d0); Button_equal = new JButton("="); Button_equal.addActionListener(new ActionListener() { public void actionPerformed(ActionEvent e) { if(opflag == true){ num2 = Double.parseDouble(num_txt); //如果此时opflag为true的话,证明已经输入运算符,这时候刚输入的数为另外一个操作数,所以赋给num2。 calc(op); //num1和num2进行运算。 } result.setText(new Double(num1).toString()); //显示结果。 } }); Button_equal.setBounds(279, 213, 50, 110); frame.getContentPane().add(Button_equal); button_plus = new JButton("+"); button_plus.addActionListener(new ActionListener() { public void actionPerformed(ActionEvent e) { opBtnAction("+"); } }); button_plus.setBounds(279, 97, 50, 50); frame.getContentPane().add(button_plus); button_sub = new JButton("-"); button_sub.addActionListener(new ActionListener() { public void actionPerformed(ActionEvent e) { opBtnAction("-"); } }); button_sub.setBounds(279, 157, 50, 50); frame.getContentPane().add(button_sub); button_mul = new JButton("*"); button_mul.addActionListener(new ActionListener() { public void actionPerformed(ActionEvent e) { opBtnAction("*"); } }); button_mul.setBounds(39, 157, 50, 50); frame.getContentPane().add(button_mul); button_div = new JButton("/"); button_div.addActionListener(new ActionListener() { public void actionPerformed(ActionEvent e) { opBtnAction("/"); } }); button_div.setBounds(39, 97, 50, 50); frame.getContentPane().add(button_div); button_clr = new JButton("clr"); button_clr.addActionListener(new ActionListener() { public void actionPerformed(ActionEvent e) { result.setText(null); //清楚文本框和num_txt,num1和num2全部置为0, txt = null; //numflag和opflag均置为false,全部置为程序开始的默认值。 numflag = opflag = false; num1 = num2 = 0; num_txt = ""; } }); button_clr.setBounds(39, 273, 50, 50); frame.getContentPane().add(button_clr); button_dlt = new JButton("dlt"); button_dlt.addActionListener(new ActionListener() { public void actionPerformed(ActionEvent e) { if(num_txt != "" && num_txt.length() > 0) { num_txt = num_txt.substring(0, num_txt.length() - 1); //通过截取字符串的方式回删一个字符 } if(txt != null && txt.length() > 0) { txt = result.getText().substring(0,txt.length() - 1); //结果文本框的回删 result.setText(txt); } } }); button_dlt.setBounds(39, 213, 50, 50); frame.getContentPane().add(button_dlt); } private void numBtnAction(String num) { if(num_txt == "" && opflag == false) { //判断是否num_txt是否为空,opflag是否为false,若满足这两个 result.setText(null); //条件,则为一次运算完毕,切新运算不以该次结果继续做运算。 num_txt = ""; } numflag = true; //只要输入一个数,则把numflag置为true,表示已有数字输入 num_txt += num; //把输入的数加入到最终要转换成都double运算的字符串 txt = result.getText() + num; //加到txt,使输入的数显示到文本框中。 result.setText(txt); } private void opBtnAction(String operator) { if(opflag == false && num_txt != "") { //进行判断,如果opflag为false,则表示还没输入运算符, num1 = Double.parseDouble(num_txt); //这个时候把num_txt转换成double赋给num1。 } if(opflag == true && num_txt != ""){ num2 = Double.parseDouble(num_txt); //如果opflag为true,表示第一个数输入完毕,且已输入相应的运算符,这个时候是在输入第二个要参与运算的数,则加到num2 calc(op); //先计算两数结果,赋给num1,num2置为0,以便后面多层混合运算使用。 } numflag = false; //numflag置为0,表示当前需要输入数进行运算 op = operator; //把新输入的运算符赋给op result.setText(operator + " "); //在文本框显示 opflag = true; //opflag置为true,表示当前已输入一个或多个操作数。 num_txt = ""; //num_txt置为空,为了存储下一个操作数。 } private void calc(String op) { switch(op){ case "+" : num1 = num1 + num2; num2 = 0; opflag = false; num_txt = ""; break; case "-" : num1 = num1 - num2; num2 = 0; opflag = false; num_txt = ""; break; case "*" : if(num2 != 0) { num1 = num1 * num2; num2 = 0; opflag = false; num_txt = ""; } break; case "/" : if(num2 != 0) { num1 = num1 / num2; num2 = 0; opflag = false; num_txt = ""; } break; default: opflag = false; num_txt = ""; break; } }}
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